diff --git a/src/atom/service.py b/src/atom/service.py
index 306bcd9f..b399cff4 100644
--- a/src/atom/service.py
+++ b/src/atom/service.py
@@ -181,7 +181,8 @@ class AtomService(object):
       if content_length:
         all_headers['Content-Length'] = str(content_length)
 
-    all_headers['GData-Version'] = '2.0'
+    if 'GData-Version' not in all_headers:  
+      all_headers['GData-Version'] = '2.0'
     # Find an Authorization token for this URL if one is available.
     if self.override_token:
       auth_token = self.override_token